Cushion and cushion to frame assembly mechanism for patient interface

ABSTRACT

A full-face cushion for a patient interface that delivers breathable gas to a patient includes a frame connector adapted to attach the cushion to a mask frame and an interface provided to the frame connector. The interface is constructed of foam and defines a cushion cavity. The interface includes a foam contact surface adapted to interface or contact with surfaces of the patient&#39;s face in use.

CROSS-REFERENCE TO APPLICATIONS

This application claims the benefit of U.S. Provisional Application Nos. 60/935,336, filed Aug. 8, 2007, and 60/907,856, filed Apr. 19, 2007, each of which is incorporated herein by reference in its entirety.

Also, PCT Publication No. WO 2006/074513, published Jul. 20, 2006, and PCT Application No. PCT/AU2006/000035, filed Jan. 12, 2006, are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to a cushion for a patient interface used in the treatment, e.g., of Sleep Disordered Breathing (SDB) with Non-Invasive Positive Pressure Ventilation (NPPV). The present invention also relates to a method and apparatus for assembling a cushion to a frame of the patient interface.

BACKGROUND OF THE INVENTION

PCT Publication No. WO 2006/074513 and PCT Application No. PCT/AU2006/000035 describe embodiments of a cushion and a cushion to frame assembly mechanism.

SUMMARY OF THE INVENTION

One aspect of the present invention relates to improvements and/or alternative arrangements of the cushion and cushion to frame assembly mechanism described in PCT Publication No. WO 2006/074513 and PCT Application No. PCT/AU2006/000035 to enhance respiratory therapy.

Another aspect of the invention relates to a full-face cushion for a patient interface that delivers breathable gas to a patient. The full-face cushion includes a frame connector adapted to attach the cushion to a mask frame and an interface provided to the frame connector. The interface is constructed of foam and defines a cushion cavity. The interface includes a foam contact surface adapted to interface or contact with surfaces of the patient's face in use.

Another aspect of the invention relates to a full-face cushion for a patient interface that delivers breathable gas to a patient. The full-face cushion includes a membrane including a uniform wall thickness in the range of 0.15-0.30 mm around the perimeter of the cushion and a foam insert provided to the membrane to support the membrane. The foam insert is structured to provide a variable spring component to the membrane. In alternative embodiments, the thickness of the membrane could be variable from 0.15-0.7 mm, e.g., depending on location around the perimeter of the cushion.

Another aspect of the invention relates to a full-face cushion for a patient interface that delivers breathable gas to a patient. The full-face cushion includes a side wall, a membrane extending away from the side wall and adapted to form a continuous seal on the patient's face in use, and one or more ribs provided to the side wall to vary its spring characteristic.

Another aspect of the invention relates to a full-face cushion for a patient interface that delivers breathable gas to a patient. The full-face cushion includes a frame connector adapted to attach the cushion to a mask frame, a side wall extending away from the frame connector, and a membrane extending away from the side wall and adapted to form a continuous seal on the patient's face in use. The side wall is angled outwardly with respect to the frame connector by an angle to vary the spring characteristic, and the angle may be different in different regions of the cushion.

Another aspect of the invention relates to a full-face cushion for a patient interface that delivers breathable gas to a patient. The full-face cushion includes a membrane including a wall thickness less than 0.3 mm provided in at least a region of the cushion. The thickness may be between about 0.15 mm to 0.30 mm. In alternative embodiments, the thickness of the membrane could be variable from 0.15-0.7 mm, e.g., depending on location around the perimeter of the cushion.

Another aspect of the invention relates to a full-face cushion for a patient interface that delivers breathable gas to a patient. The full-face cushion includes a side wall, an underlying support cushion extending away from the side wall, and a membrane provided to substantially cover at least a portion of the underlying cushion. The underlying support cushion is provided in at least side of nose, upper cheek, lower cheek, and mouth/chin regions of the cushion, and the underlying support cushion in the mouth/chin region has a smaller wall thickness than the other regions.

Another aspect of the invention relates to a full-face mask assembly including a frame, a cushion provided to the frame, and a clip to maintain the cushion to the frame. The cushion is adapted to form a seal around the patient's nose and mouth. The clip includes three clip portions adapted to engage the frame, and the clip includes a flange that extends around the perimeter and three cut-outs are provided in the flange adjacent respective clip portions.

Other aspects, features, and advantages of this invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which are a part of this disclosure and which illustrate, by way of example, principles of this invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings facilitate an understanding of the various embodiments of this invention. In such drawings:

FIGS. 1-1 to 1-2 illustrate a foam cushion according to an embodiment of the present invention;

FIG. 1-3 illustrates a foam cushion with different stiffnesses according to an embodiment of the present invention;

FIG. 2-1 illustrates a cushion including a foam insert according to an embodiment of the present invention;

FIG. 3-1 illustrates a cushion including ribs according to an embodiment of the present invention;

FIG. 3-2 illustrates a cushion including ribs according to another embodiment of the present invention;

FIG. 4-1 illustrates a cushion including and angled side wall according to an embodiment of the present invention;

FIGS. 5-1 to 5-3 illustrate a cushion including a very thin membrane wall thickness according to an embodiment of the present invention;

FIGS. 6-1 to 6-6 illustrate a cushion including a thinned undercushion in a mouth/chin region according to an embodiment of the present invention;

FIG. 7-1 illustrates a cushion to frame assembly mechanism according to an embodiment of the present invention; and

FIG. 7-2 is a cross-sectional view illustrating the engagement between the cushion clip, cushion, and frame according to an embodiment of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

The following description is provided in relation to several embodiments which may share common characteristics and features. It is to be understood that one or more features of any one embodiment may be combinable with one or more features of the other embodiments. In addition, any single feature or combination of features in any of the embodiments may constitute additional embodiments.

In this specification, the word “comprising” is to be understood in its “open” sense, that is, in the sense of “including”, and thus not limited to its “closed” sense, that is the sense of “consisting only of”. A corresponding meaning is to be attributed to the corresponding words “comprise”, “comprised” and “comprises” where they appear.

Each illustrated embodiment includes features that may be adapted for use and/or incorporated into the embodiments and/or components of the cushion and/or cushion to frame assembly mechanism described in PCT Publication No. WO 2006/074513 and PCT Application No. PCT/AU2006/000035, as would be apparent to those of ordinary skill in the art. PCT Publication No. WO 2006/074513 and PCT Application No. PCT/AU2006/000035 are each incorporated herein by reference in its entirety.

While each illustrated embodiment is described as being implemented into a cushion and/or cushion to frame assembly mechanism of the type described in PCT Publication No. WO 2006/074513 and PCT Application No. PCT/AU2006/000035, each illustrated embodiment may be implemented into other masks, e.g., full-face mask, mouth mask, nasal mask, nasal prongs, nozzles, nare seals, and/or cannulae.

1. Improvements/Alternative Arrangements

The following embodiments describe improvements and/or alternative arrangements of the cushion and cushion to frame assembly mechanism described in PCT Publication No. WO 2006/074513 and PCT Application No. PCT/AU2006/000035 to enhance respiratory therapy.

2. Variable Spring Characteristic of Cushion

PCT Publication No. WO 2006/074513 discloses a cushion having a varying cross-section around its perimeter to tailor or vary the spring characteristic.

2.1 Foam Cushion to Vary Spring Characteristic

In an alternative embodiment, a cushion may be constructed of a foam material to vary the spring characteristic. For example, FIGS. 1-1 and 1-2 illustrate a foam cushion 10 constructed of a foam material F. As illustrated, the foam cushion 10 provides a foam interface that defines a cushion cavity 11 and includes a foam contact surface 12 adapted to interface or contact with surfaces of the patient's face in use. The foam contact surface 12 may have a similar contour or geometry to that of the cushion illustrated in PCT Publication No. WO 2006/074513. However, the foam contact surface may have other suitable contours or geometries, e.g., to accommodate contours of a particular patient's face.

The foam material F may include one or more of the foam properties described in U.S. Provisional Application No. 60/874,968, filed Dec. 15, 2006, and U.S. Provisional Application No. 60/833,841, filed Jul. 28, 2006, each of which is incorporated herein by reference in its entirety. For example, the foam material may be visco-elastic, de-skinned, etc.

In the illustrated embodiment, the foam cushion 10 includes a frame connector 14 in the form of a grooved portion adapted to attach the cushion to a mask frame. However, the foam cushion 10 may include other suitable frame connectors for attachment to the mask frame, e.g., Velcro®, cushion clip, relatively rigid base, etc.

Also, the foam cushion 10 may include different stiffnesses (e.g., by varying the density) in order to vary the spring characteristic. The stiffness of the cushion may be varied in different regions of the cushion, e.g., to tailor the cushion for a particular patient. For example, as shown in FIG. 1-3, the foam cushion may include a relatively softer, less dense foam in nasal bridge and chin regions NB, C, and a relatively harder, more dense foam in cheek regions CH. This arrangement provides higher flexibility in the nasal bridge and chin regions NB, C and lower flexibility in the cheek regions CH, e.g., for stability. However, the foam cushion may have other suitable characteristics around its perimeter.

In an alternative embodiment, foam may be provided in some regions of the cushion and a silicone membrane may be provided in other regions of the cushion. For example, foam may only be used in the cheek region and the silicone membrane may be used in the nasal bridge and chin regions. In this arrangement, support is only provided by the sturdy, less sensitive cheek structures and is less prone to cause an out of balance mask due to protruding or weak chins.

2.2 Foam Insert

In another alternative embodiment, a foam insert may be used in a cushion to vary the spring characteristic. For example, FIG. 2-1 illustrates a cushion 20 including a relatively thin membrane 22 (e.g., of uniform thickness around the entire perimeter (e.g., 0.15-0.3 mm)) and a foam insert 25 provided to the cushion 20 to support the membrane 22 and provide a variable spring component. For example, the membrane may provide a relatively constant or no spring component and the foam insert may provide a variable spring component to vary the spring characteristic of the cushion. In alternative embodiments, the thickness of the membrane could be variable from 0.15-0.7 mm, e.g., depending on location around the perimeter of the cushion.

The foam insert 25 may include one or more of the foam properties described in U.S. Provisional Application No. 60/874,968, filed Dec. 15, 2006, and U.S. Provisional Application No. 60/833,841, filed Jul. 28, 2006, each of which is incorporated herein by reference in its entirety. For example, the foam insert may be visco-elastic, de-skinned, etc.

The foam insert 25 may be retained to the cushion 20 in any suitable manner, e.g., friction-fit, adhesive, mechanical interlock, etc.

Similar to the above, the foam insert 25 may include different stiffnesses (e.g., by varying the density) in order to vary the spring characteristic. The stiffness of the foam insert 25 may be varied in different regions, e.g., to tailor the foam insert for a particular patient.

In an embodiment, the foam insert 25 may be removably mounted or retro-fit to the cushion 20 so that different foam inserts may be used in the cushion from night to night and/or a foam insert may be optionally used in the cushion, e.g., foam insert used on alternate nights.

Also, in an alternative embodiment, a foam insert may only be provided in selected regions of the cushion in order to vary the spring characteristic in the selected region. For example, a foam insert may only be used in the cheek region which provides a sturdy, less sensitive support.

In another embodiment, the base of the foam insert may be angled in selected regions so that compression of the foam insert is normal or perpendicular to facial structures, e.g., base of the foam insert angled to align the membrane to be perpendicular to the sides of the patient's nose.

2.3 Cushion with Ribs

In another alternative embodiment, a cushion may be provided with one or more ribs to vary the spring characteristic. For example, FIG. 3-1 illustrates a cushion 30 including a series of ribs 32 that extend around the perimeter of the cushion. The ribs 32 may be integrally formed with the cushion and/or attached to the cushion, e.g., by an adhesive.

In the illustrated embodiment, the series of ribs 32 are provided to an external surface of the cushion, e.g., along an external surface of the cushion side wall. However, the ribs may be provided to other suitable portions of the cushion, e.g., along an internal surface of the cushion side wall.

Also, each rib 32 includes an elongated configuration and extends vertically along the cushion side wall in spaced apart relation from the other ribs. However, the ribs may have other suitable configurations and arrangements to vary the spring characteristic, e.g., different shape, length, width, thickness, spacing around perimeter, orientation, etc. For example, FIG. 3-2 illustrates a cushion including a series of interconnected ribs 34.

In addition, the rib configuration and/or arrangement may be varied in different regions of the cushion, e.g., to tailor the stiffness of the cushion for a particular patient. For example, the cushion may include no ribs in nasal bridge and chin regions to allow higher flexibility in these regions, and the cushion may include a series of ribs in cheek regions to allow lower flexibility in these regions, e.g., for stability. However, the rib configuration and/or arrangement may be varied in other suitable manners around the cushion perimeter.

In an embodiment, the ribs may replace an underlying support cushion or undercushion to vary the spring characteristic. In another embodiment, the ribs may be used in conjunction with an undercushion to vary the spring characteristic.

2.4 Angled Cushion Shape

PCT Publication No. WO 2006/074513 discloses a cushion wherein one or more portions have a sickle-shaped cross-sectional configuration. In an alternative embodiment, the cushion may have one or more portions with an angled-shaped cross-sectional configuration to vary the spring characteristic. For example, FIG. 4-1 illustrates a cushion 40 including a membrane 42, an optional underlying support cushion or undercushion 44, a base or side wall 46, and a frame connector 48 adapted to attach the cushion to a mask frame.

In the illustrated embodiment, the side wall 46 is angled outwardly with respect to the frame connector 48 by an angle α. The angle α may be varied to vary the spring characteristic provided by such angled side wall. However, other cushion parameters may be varied to vary the spring characteristic, e.g., wall thickness, length, undercushion radius, etc.

In addition, the angle a and/or other cushion parameters may be varied in different regions of the cushion, e.g., to tailor the stiffness of the cushion for a particular patient. For example, the angle α may be varied to allow higher flexibility in more sensitive regions, e.g., nasal bridge region, and lower flexibility in less sensitive regions, e.g., cheek region. However, the angle α and/or other cushion parameters may be varied in other suitable manners around the cushion perimeter.

3. Nasal Bridge Region of Cushion

PCT Publication No. WO 2006/074513 discloses a cushion having a membrane with a relatively thin wall thickness in the nasal bridge region, e.g., 0.3 mm thick.

3.1 Very Thin Membrane Wall Thickness

In an alternative embodiment, one or more regions of a cushion may have a membrane with a wall thickness less than 0.3 mm thick. For example, FIGS. 5-1 to 5-3 illustrate a cushion 50 having a membrane 52 with a wall thickness of about 0.15 mm. As illustrated, such 0.15 mm membrane wall thickness is provided in a nasal bridge region NB and a side of nose and/or upper cheek region UC of the cushion. Other regions of the cushion, e.g., lower cheek and chin regions, may have thicker membrane wall thicknesses, e.g., 0.5 mm. This arrangement provides higher flexibility in more sensitive regions, e.g., nasal bridge and upper cheek regions, and lower flexibility in less sensitive regions, e.g., cheek and chin regions. However, the wall thickness of the membrane may be varied in other suitable manners around the cushion perimeter. In alternative embodiments, the thickness of the membrane could be variable from 0.15-0.7 mm, e.g., depending on location around the perimeter of the cushion.

4. Mouth/Chin Region of Cushion

PCT Publication No. WO 2006/074513 discloses a cushion that includes a cut-out of the undercushion in the mouth/chin region.

4.1 Thinned Section for Undercushion

In an alternative embodiment, the mouth/chin region of the cushion may include an undercushion. For example, FIGS. 6-1 to 6-6 illustrate a cushion 60 including a membrane 62 and an underlying support cushion or undercushion 64 provided to side of nose region SN, upper cheek region UC, lower cheek region LC, and mouth/chin region C of the cushion. Although an undercushion is not illustrated in the nasal bridge region NB (e.g., see FIG. 6-2), the cushion may include an undercushion in the nasal bridge region NB in an alternative embodiment, e.g., undercushion extends around entire perimeter of the cushion.

In the illustrated embodiment, the wall thickness of the undercushion in the mouth/chin region C may be thinner than the undercushion in other regions of the cushion. For example, as shown in FIGS. 6-3 to 6-6, the wall thicknesses of the undercushion 64 in the side of nose region SN, upper cheek region UC, and lower cheek region LC are thicker than the undercushion 64 in the mouth/chin region C. This arrangement provides higher flexibility in the mouth/chin region C, which may be more sensitive. However, the wall thickness of the undercushion may be varied in other suitable manners around the cushion perimeter.

4.2 Series of Ribs

In another alternative embodiment, the undercushion may be replaced with a series of ribs that extend around the perimeter of the cushion, e.g., ribs of varying thickness and/or width to vary the spring characteristic. Further details and arrangements of such ribs are described above in section 2.3.

5. Cushion to Frame Assembly Mechanism

PCT Application No. PCT/AU2006/000035 discloses a mask assembly including an internal-style cushion clip with three attachment points to removably connect a cushion to a mask frame.

5.1 Cushion to Cushion Clip Attachment

In an embodiment, the mask assembly may include a cushion clip with three cut-outs that are adapted to interlock with respective solid sections provided in the retaining recess of the cushion.

For example, FIG. 7-1 illustrates a cushion clip 70 including side clip portions 72, 74 and a bottom clip portion 76 adapted to engage respective slots 92 provided on the frame 90 (one of the slots hidden in FIG. 7-1). It should be appreciated that the cushion clip 70 may have any suitable number of clip portions, and the number of slots in the frame 90 may be varied according to the number of clip portions. Also, the cushion clip 70 includes a flange 78 around the perimeter, and slots or cut-outs 80 are provided in the flange 78 adjacent respective clip portions 72, 74, 76.

In use, the cushion clip 70 is first assembled or interlocked with the cushion 95 to provide a cushion clip/cushion sub-assembly, and then the cushion clip/cushion sub-assembly is engaged with the frame 90 by inserting the clip portions 72, 74, 76 of the cushion clip 70 into respective slots 92 of the frame 90, e.g., with a snap-fit.

The cushion clip 70 is assembled to the cushion 95 by engaging the flange 78 of the cushion clip 70 within the retaining recess 96 of the cushion 95. The cut-outs 80 in the cushion clip 70 are adapted to interlock or engage with respective solid sections 98 provided in the retaining recess, i.e., solid sections provided on opposing sides and the bottom of the cushion. The three cut-outs/solid sections assist with correct orientation or alignment of the cushion clip 70 onto the cushion 95. However, other suitable numbers of cut-outs/solid sections may be provided.

FIG. 7-2 is an exemplary cross-sectional view illustrating the engagement between the cushion clip 70, cushion 95, and frame 90. As illustrated, the cushion 95 is sandwiched between inner and outer walls 93, 94 of the frame 90 and the cushion 95 may include a lip seal 97 adapted engage the inner wall 93 and provide a seal.

In the illustrated embodiment, the side clip portions 72, 74 include a different structure or configuration than the bottom clip portion 76. As illustrated, the side clip portions 72, 74 are relatively thick and include contoured finger grips 82 to facilitate assembly. The bottom clip portion 76 has a lower profile than the side clip portions 72, 74 and does not provide finger grips. However, the clip portions 72, 74, 76 may have other suitable arrangements, e.g., bottom clip portion similar structure to side clip portions.

While the invention has been described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Also, the various embodiments described above may be implemented in conjunction with other embodiments, e.g., aspects of one embodiment may be combined with aspects of another embodiment to realize yet other embodiments. Further, each independent feature or component of any given assembly may constitute an additional embodiment. Furthermore, each individual component of any given assembly, one or more portions of an individual component of any given assembly, and various combinations of components from one or more embodiments may include one or more ornamental design features. In addition, while the invention has particular application to patients who suffer from OSA, it is to be appreciated that patients who suffer from other illnesses (e.g., congestive heart failure, diabetes, morbid obesity, stroke, bariatric surgery, etc.) can derive benefit from the above teachings. Moreover, the above teachings have applicability with patients and non-patients alike in non-medical applications. 

1. A full-face cushion for a patient interface that delivers breathable gas to a patient, the full-face cushion comprising: a frame connector adapted to attach the cushion to a mask frame; and an interface provided to the frame connector, the interface being constructed of foam and defining a cushion cavity, the interface including a foam contact surface adapted to interface or contact with surfaces of the patient's face in use.
 2. The full-face cushion according to claim 1, wherein the interface includes different stiffnesses in different regions of the cushion to vary the spring characteristic.
 3. The full-face cushion according to claim 1, wherein the interface includes a relatively softer, less dense foam in a nasal bridge region and/or a chin region of the cushion.
 4. The full-face cushion according to claim 1, wherein selected regions of the interface include foam and the other regions of the interface include a silicone membrane.
 5. The full-face cushion according to claim 4, wherein the foam is provided in the cheek region.
 6. A full-face cushion for a patient interface that delivers breathable gas to a patient, the full-face cushion comprising: a membrane including a uniform wall thickness in the range of 0.15-0.30 mm around the perimeter of the cushion; and a foam insert provided to the membrane to support the membrane, the foam insert structured to provide a variable spring component to the membrane.
 7. The full-face cushion according to claim 6, wherein the foam insert includes different stiffnesses in different regions thereof.
 8. The full-face cushion according to claim 6, wherein the foam insert is removably mounted to the membrane.
 9. The full-face cushion according to claim 6, wherein the foam insert is provided to selected regions of the membrane.
 10. The full-face cushion according to claim 9, wherein the foam insert is provided in the cheek region.
 11. The full-face cushion according to claim 6, wherein a base of the foam insert is angled to align the membrane to be perpendicular to facial structures.
 12. The full-face cushion according to claim 11, wherein the base of the foam insert is angled to align the membrane to be perpendicular to the sides of the patient's nose.
 13. A full-face cushion for a patient interface that delivers breathable gas to a patient, the full-face cushion comprising: a side wall; a membrane extending away from the side wall and adapted to form a continuous seal on the patient's face in use; and one or more ribs provided to the side wall to vary its spring characteristic.
 14. The full-face cushion according to claim 13, wherein a series of ribs extends around the perimeter of the cushion in spaced apart relation.
 15. The full-face cushion according to claim 13, wherein the one or more ribs provide different stiffnesses in different regions of the cushion.
 16. The full-face cushion according to claim 13, wherein the shape, length, width, thickness, spacing, and/or orientation of the ribs is variable to vary the spring characteristic.
 17. The full-face cushion according to claim 13, further comprising an underlying support cushion extending away from the side wall and having at least a portion substantially covered by the membrane.
 18. A full-face cushion for a patient interface that delivers breathable gas to a patient, the full-face cushion comprising: a frame connector adapted to attach the cushion to a mask frame; a side wall extending away from the frame connector; and a membrane extending away from the side wall and adapted to form a continuous seal on the patient's face in use, wherein the side wall is angled outwardly with respect to the frame connector by an angle to vary the spring characteristic.
 19. The full-face cushion according to claim 18, wherein the angle is different in different regions of the cushion.
 20. The full-face cushion according to claim 18, further comprising an underlying support cushion extending away from the side wall and having at least a portion substantially covered by the membrane.
 21. A full-face cushion for a patient interface that delivers breathable gas to a patient, the full-face cushion comprising: a membrane including a wall thickness less than 0.3 mm provided in at least a region of the cushion.
 22. The full-face cushion according to claim 21, wherein the wall thickness is about 0.15 mm.
 23. The full-face cushion according to claim 21, wherein the wall thickness less than 0.3 mm is provided in at least a nasal bridge region of the cushion.
 24. A full-face cushion for a patient interface that delivers breathable gas to a patient, the full-face cushion comprising: a side wall; an underlying support cushion extending away from the side wall; and a membrane provided to substantially cover at least a portion of the underlying cushion, wherein the underlying support cushion is provided in at least side of nose, upper cheek, lower cheek, and mouth/chin regions of the cushion, and the underlying support cushion in the mouth/chin region has a smaller wall thickness than the other regions.
 25. A full-face mask assembly, comprising: a frame; a cushion provided to the frame, the cushion adapted to form a seal around the patient's nose and mouth; and a clip to maintain the cushion to the frame, wherein the clip includes three clip portions adapted to engage the frame, and the clip includes a flange that extends around the perimeter and three cut-outs are provided in the flange adjacent respective clip portions.
 26. The full-face mask assembly according to claim 25, wherein the flange is adapted to engage within a retaining recess provided to the cushion, and the three cut-outs in the flange are adapted to interlock with a respective solid section provided within the retaining recess of the cushion.
 27. The full-face mask assembly according to claim 25, wherein one of the clip portions has a different structure or configuration than the other of the clip portions. 